Trump tweeted that "Apple prices may increase because of the massive Tariffs we may be imposing on China - but there is an easy solution where there would be ZERO tax, and indeed a tax incentive. Make your products in the United States instead of China. Start building new plants now."

Apple declined to comment.

The technology sector is among the biggest potential losers as tariffs would make imported computer parts more expensive. Apple's AirPods headphones, some of its Beats headphones and its new HomePod smart speaker would also face levies.

"The burden of the proposed tariffs will fall much more heavily on the United States than on China," Apple said in its letter.